Experimental assessment of temperature effect on open-hole notch sensitivity in woven carbon fiber composites

Abstract

Composite laminates often comprise notch-like features such as drilled assembly holes or geometric discontinuities resulting from damage. These features induce stress concentrations in their vicinities and can, through incompletely understood temperature-dependent damage mechanisms, reduce laminates’ load carrying capacity. Accordingly, this work investigates the effect of elevated temperatures on the notch sensitivity of carbon fiber-reinforced polymer composites and on the initiation and progression of notch-triggered damage mechanisms. This work employs an experimental approach in which tensile notched and un-notched specimens are loaded in controlled temperatures. Specimens are tested at multiple temperatures, and their nominal and local behavior in the vicinity of a circular notch are observed using digital image correlation. Results demonstrated a decreasing trend in the elastic moduli and ultimate tensile strength of notched specimens with increasing temperatures. However, the global response of notched samples at 50 $$^{\circ }$$ C surprisingly deviated from the expected trend and exhibited 8% higher tensile strength than that observed at 25 $$^{\circ }$$ C. Moreover, the notch sensitivity was found to decrease with increasing temperatures. Two main temperature-sensitive notch-triggered damage mechanisms were observed, namely transverse cracks and axial splitting. Transverse cracks were evident at all considered temperatures, while axial splitting was absent at room temperature.